1. Field of the Invention
The present invention relates to a golf ball having an outer cover, and an inner cover whose hardness is lower than that of the outer cover. More particularly it relates to a golf ball capable of providing a high ballistic trajectory while maintaining high resilience and capable of providing a player with good feel on impact.
2. Related Art
Generally, a softer golf ball exhibits a larger launch angle. Conventionally, therefore, in order to obtain a golf ball exhibiting a high ballistic trajectory with a large launch angle, a soft material is used to form at least one constituent layer of the golf ball. For example, a relatively soft rubber is used to form a core, or a relatively soft resin is used to form an inner or outer cover (may be referred to as an intermediate layer or a cover).
However, in the method of forming a core through use of a soft rubber, when the core is made excessively soft, the ball becomes excessively soft. As a result, in spite of a high ballistic trajectory, resilience decreases, and thus travel distance becomes relatively short. Further, upon a full shot (strong hit), the ball gives a player an impression like that of a coreless ball.
Also, during putting, a sound of the hit becomes low, giving an unfavorable impression to many players.
In the method of forming an inner or outer cover through use of a soft resin, when the resin is excessively soft or the resin layer is excessively thick, the ball becomes excessively soft. As a result, in spite of a high ballistic trajectory, resilience decreases, and thus travel distance becomes relatively short. Further, upon a full shot (strong hit), the ball gives a player an impression like that of a coreless ball.